1. Field of the Invention
The present invention relates to a bendable portion control mechanism of an endoscope.
2. Description of the Related Art
A typical endoscope with a bendable portion capable of being freely bent in four directions (upward, downward, leftward and rightward) is provided with a U-D control knob for bending the bendable portion upward and downward, an R-L control knob for bending the bendable portion rightward and leftward, a U-D bent state holding mechanism for holding a bent state of the bendable portion in the upward/downward direction by exerting frictional resistance on the rotating operation of the U-D control knob, and an R-L bent state holding mechanism for holding a bent state of the bendable portion in the rightward/leftward direction by exerting frictional resistance on the rotating operation of the R-L control knob in the control portion of the endoscope. The U-D control knob and the R-L control knob are coaxially arranged so that one thereof is provided on top of the other, so that each of the U-D control knob and the R-L control knob can be freely rotated on a common axis, and are installed in water-sealed spaces together with the U-D bent state holding mechanism and the R-L bent state holding, respectively, to prevent the entry of water from the outside the endoscope. This structure is disclosed in, e.g., Japanese unexamined patent publications H09-98942, H06-327613, H10-286220 and H11-47082.
In endoscopes provided with such bent state holding mechanisms to hold a bent state of the bendable portion, it is necessary to make an adjustment to the operational characteristics of each bent state holding mechanism (e.g., to make an adjustment to the degree of frictional resistance produced by the bent state holding mechanism) by checking whether or not the bendable portion is in an appropriate bent state with the bendable portion being bent by rotating the associated control knob.
However, since bent state holding mechanisms for endoscopes produced in recent years are installed in the water-sealed space of the associated control knob which is water-sealed to prevent entry of water from outside the endoscope, considering that the endoscope is washed and sterilized after use by steam or a liquid medicine, each control knob needs to be removed if it is desired adjust the operational characteristics of each bent state holding mechanism.
Nevertheless, to remove the U-D control knob or the R-L control knob (one which is provided on top of the other and coaxially arranged) which is positioned closest to the base of the control portion, the bent state holding mechanism installed in this other control knob needs to be disassembled.
Accordingly, it is troublesome to make an adjustment to the degree of frictional resistance which is exerted on the rotating operation of the control knob positioned closer to the base of the control portion; moreover, a need to make an adjustment to the degree of frictional resistance which is exerted on the rotating operation of the other control knob that is positioned farther from the base of the control portion arises after the control knob positioned closer to the base of the control portion is re-mounted to the control portion. Therefore, fine adjustments made to the endoscope during assembly of the endoscope after the bendable portion control mechanism is assembled and adjustments made to the endoscope during routine maintenance after use by the operator are very troublesome and time-consuming.